Water Heater Shut-Off

The average household water heater holds about 50 gallons of water and with a flow rate of about 20 gallons per hour, an 8-hour leak can spill over 200 gallons of water into your home. Chances are your water heater is located somewhere out of sight, so a spill can go unnoticed for a considerable amount of time. This can mean thousands of dollars in water damage and cleanup costs. Factor in the sub-freezing temperatures in winter and you have an even bigger disaster.

An easy way to prevent a water heater leak from getting out of control is to install an automatic water shut-off valve. The Floodstop water heater shutoff kit installs in minutes and will automatically shut off water to your water heater when a leak is detected.

Your first step in this project is to determine the type of kit required for your water heater. The shutoff valve will be installed in-line with the cold-water input to the water heater, so you need to find out the size of this pipe. The two most common sizes are 3/4" and 1 1/2". The 3/4" kit is also available with compression fittings that will ease installation and help seal the valve to the existing pipe.

Equipment Required

  • Floodstop Water Heater Shutoff (one of the below)
    • 3/4" valve kit
    • 1.25" valve kit
    • 3/4" compression kit
  • Additional copper pipe and fittings (as required)
  • Hacksaw (optional)
  • Pipe wrench
  • Screwdriver (optional)
  • Pipe sealant or plumbers tape (not required is using compression fittings)
  • 120VAC power outlet and/or 4 size C batteries


  • Shut off or close the water supply to your water heater at the existing manual shutoff valve.
  • Disconnect the cold water supply-line from the manual shutoff valve and the water heater input.
  • You will want to install the Floodstop valve downstream from the manual shutoff (as close to the manual shutoff valve as possible). The ideal position would be to attach the Floodstop valve directly downstream from the manual shutoff valve. If this is not possible, you will need to cut and fit copper piping as required. If you are not using compression fittings, you will need to seal the threads with pipe sealant or plumbers tape. Note: Do not grip the plastic motor drive on the Floodstop valve for leverage when tightening the fittings.
  • Once the Floodstop valve and manual shutoff valve are connected, connect the cold water supply-line to the Floodstop valve and the water heater input. Again, make sure you seal the threads with pipe sealant or plumbers tape. Note: If you are using compression fittings, do not use tape or sealant on the joints. This can degrade the seal and cause leaks.
  • Once all the fittings are connected and sealed, slowly turn on the manual shutoff valve and check for leaks. Tighten fittings and/or apply sealant as required.
  • Install the batteries into the Control Unit. If you are installing using the 120VAC power supply the batteries can power the unit in case of a power outage. If no outlet is available near the control unit, you can use the batteries as the primary power source.
  • Mount the Control Unit to a wall near the water heater using the Velcro mounting strips or screws (avoid placing where water could potentially drip onto the unit).
  • Connect the 4-pin connecter to the Control Unit and the Floodstop valve.
  • Attach the 2-pin connector to the Control Unit and the Floodstop water sensor.
  • Place the Floodstop water sensor at the base of your water heater. If you are using a metal base pan, place the sensor on a cloth or paper towel to insulate the sensor from the metal.
  • Connect the 120VAC power to the Control unit. The LED should flash one time in 6 seconds intervals letting you know the unit is on and the valve is open.
  • Drip some water onto the sensor to check that everything is working properly. If working, the alarm will sound and the valve will close (indicated by the LED on the Control Unit flashing 2 times in 6 second intervals).
  • If the system is working properly, dry off the sensor and press "Open" on the Control Unit to open the valve and reset the system.

Insteon Integration

The Floodstop Control Unit has two additional outputs for integration into alarm and home automation systems. The two-terminal (normally closed) outputs have leads included in the kit for easy integration. The ideal solution for INSTEON users would be using the I/O Linc Low Voltage / Contact Closure Interface with INSTEON Hub or an ISY Controller to receive a notification when a leak is detected. Click here for more information on INSTEON.

Other Floodstop Solutions

  • Washing Machine Shutoff Kit
  • Icemaker/Water Filter Shutoff Kit
  • 3/8" Compression Shutoff Kit. Can be used in multiple applications including toilets, sinks, water conditioners.